[2.1-scala] An example of Play 2.1 Filters

Roberto Tyley

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Jan 18, 2013, 5:16:26 AM1/18/13

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Play 2.1 Filters aren't heavily documented yet, so I thought some might like to see an example of their use - we've just updated our management-and-metrics library at the Guardian ("guardian-management") to use Play 2.1 Filters. The Filters framework makes it very easy for us to gather timing and http-status-code statistics on the responses we're passing back to the user. The filters are defined here:

https://github.com/guardian/guardian-management/blob/v5.23/management-play/src/main/scala/com/gu/management/play/metrics.scala

They're extremely simple, perhaps the only thing worth watching out for is the use of onFinalPlainResult() against the Scala 2.10 Future used by AsyncResult, ensuring we only time & count the response once it's fully completed.

The library includes an example of it's use in a example Play project:

https://github.com/guardian/guardian-management/blob/v5.23/example-play/app/conf/Management.scala#L21 - creates a 'standard set' of request metrics

https://github.com/guardian/guardian-management/blob/v5.23/example-play/app/Global.scala#L4 - registers them as Play filters so they can start counting requests

The statistics are then available as a JSON endpoint on a separate port (eg localhost:18080/management/status, while your Play app might be running on port 9000). This makes it easy to keep the stats private, and also ensures that hitting the management & status urls won't increment the stats themselves. Finally, the stats are read by a monitoring service like Graphite/Ganglia.

best regards,

Roberto Tyley

The Guardian - http://www.guardian.co.uk/